These processes, subject to the basic modes which are very old and largely immutable, have different characteristics when they refer to red or white wine and, thereafter, according to the grape variety, the area, the regional or local traditions and, not least, customizations specific to each winery.
In general, technical progress has brought a much more scientific approach in the process of winemaking, from the past, which has raised the quality of products and has allowed a better control of the organoleptic properties of wines as well as the presence and concentration of certain substances.
Among the vinification processes there are particular ones, directed to sparkling white wines, which require a second fermentation: in bottles for champagne method (also called classic method) or by autoclaving, for the method called Martinotti or Charmat.
This method, also called ‘of second fermentation in autoclave’, provides that the wine is moved between various pressurized tanks by pumps and external piping, which though hygienically controlled, do not completely avoid contamination of the product which may affect its preservation.
In fact, the sparkling process in autoclave, suitable for aromatic and/or fruity wines, gives rise to products not suitable for aging, but which have to be drunk preferably within the year, which are also defined, by the experts, ‘ready to drink’.
An example of this type of conventional fermentation technology is described, for example, in U.S. Pat. No. 4,593,611 which proposes adaptations improvement of conventional plants in which the wine is transferred between different tanks via pumps and pipes. In an embodiment of the cited patent, the wine is recirculated continuously and fed back into the fermentation tank through pipes with a star shape with holes or nozzles and arranged at three different heights inside the tank, namely at the bottom, at an intermediate height and the upper part of the tank above the level of the liquid. Moreover, the cited patent discloses that along the path of the pipelines, outside the tank, may be heat exchangers and other devices between which also valves for the intake of air in the piping in order to oxygenate the wine. As already mentioned, a solution such as that above provides that the wine has continually to pass through pipes that run outside the fermentation tank and equipped with various devices such as the aforementioned heat exchangers, valves, pumps, which, being in some cases removable to be used in association with different tanks, may cause contamination of wine. Furthermore, the said apparatus, although allowing to oxygenate the wine through addition of air, does not allow to exactly adjust the amount of air present inside the tank nor allows to use the same air to keep moving the wine inside the tank. With such apparatuses it is therefore always necessary to provide for the addition of chemical products that serve to stabilize and preserve the wine.
It is known that in order to stabilize and preserve the wine, while preserving perfumes and aromas, sulphites are used, such as sulfur dioxide, sodium bisulfite, and others, added in the appropriate concentration, subjected to precise limits of law.
The sulfur dioxide is added and is also generated spontaneously by the fermentation of the grape skins.
Sulfites, which incidentally are used as preservatives in many other foods, are not considered harmful to health products, at least with low concentrations, but the overall trend is to reduce them, especially for certain lines of products defined biological.
The law provides for the wine, with concentrations below 10 mg/l, may be omitted, on the label, the word «contain sulfites».
The aforementioned technical progress has obviously affected all equipment used in winemaking, so that even those of more ancient origin, such as the tanks, have evolved to become tanks equipped with modern and sophisticated devices, often controlled by computers.
The same applicant, dated Nov. 18, 2009 filed the patent application for industrial invention n. PT2009A000018 entitled ‘Serbatoio destinato al controllo dei processi di vinificazione, affinamento e conservazione dei vini e, in genere, per il mescolamento e il mantenimento dei liquidi con sostanze in sospensione e per l'insufflazione di gas tecnici’, in which is protected a technical solution in which is provided a pipe, arranged substantially in axis with the tank and extending vertically towards the bottom of the latter, operated with movement of up and down by an actuator displaced superiorly to the tank itself.
At the lower end of the pipe it is made integral with a plate or disc, which during the aforesaid up and down movement performs an action of flapping in the liquid in which it is immersed.
Inside the pipe there is provided a non-return valve, combined with a suitable filter, which allows the liquid to enter from the lower opening of the pipe during the movement downwards, preventing subsequently, when moving upwards, the outlet, so that with the succession of up and down strokes the pipe is progressively ‘loaded’ with the liquid; the latter flows from a slot provided in the pipe above the level of the liquid, going to ‘water’ the marc hat.
The wine-making tank proposed with the patent application cited above allows an effective movement of the must without having to provide pumps and pipes external to the tank and therefore without any risk of contamination of wine contained in it.
In said tank is also provided a system for the insufflation of technical gases, such as inert materials such as nitrogen argon, carbon dioxide, or possibly treated air, with said system comprising nozzles arranged in the lower part of the tank.
The insufflation system referred to in the above, enables to control, among other things, the dynamics of the fermentation process, by dosing at will the amount of oxygen contained in the liquid, eliminating it completely, by means of blowing of only inert gases, if you want to stop the oxidation and prolong the wine preservation time. In this way it is possible to reduce the amount of sulfite to be added for proper preservation. In addition, the blowing of gas from the bottom of the tank also involves handling of the lees which tend to settle on the bottom. This handling operation of the lees is extremely desirable in certain stages of the fermentation process while it is entirely undesirable and has to be avoided in other phases, which must then be performed by stopping the blowing of gas or transferring the wine to other types of tanks.